[PATCH v13 18/33] hw/s390x/ipl: Rework s390_ipl_map_iplb_chain for certificate storage

[Zhuoying Cai <zycai@linux.ibm.com>]

Rework s390_ipl_map_iplb_chain to always allocate maximum memory for
the IPLB chain, regardless of the number of boot devices. This space
is also used to store certificates during secure boot, providing a
safe location for certificates until the kernel reads them during boot.

Rename next_iplb to ipl_data to better reflect its multiple purposes:
storing both IPLB chains and certificate data.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
---
 hw/s390x/ipl.c              | 17 +++++++++++++----
 include/hw/s390x/ipl/qipl.h |  3 ++-
 pc-bios/s390-ccw/iplb.h     |  4 ++--
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index f9f14d7b67..af89005790 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -425,10 +425,9 @@ static S390PCIBusDevice *s390_get_pci_device(DeviceState *dev_st, int *devtype)
     return pbdev;
 }
 
-static uint64_t s390_ipl_map_iplb_chain(IplParameterBlock *iplb_chain)
+static uint64_t s390_ipl_map_iplb_chain(IplParameterBlock *iplb_chain, uint16_t count)
 {
     S390IPLState *ipl = get_ipl_device();
-    uint16_t count = be16_to_cpu(ipl->qipl.chain_len);
     uint64_t len = sizeof(IplParameterBlock) * count;
     uint64_t chain_addr = find_iplb_chain_addr(ipl->bios_start_addr, count);
 
@@ -592,7 +591,7 @@ void s390_rebuild_iplb(uint16_t dev_index, IplParameterBlock *iplb)
 static bool s390_init_all_iplbs(S390IPLState *ipl)
 {
     int iplb_num = 0;
-    IplParameterBlock iplb_chain[7];
+    IplParameterBlock iplb_chain[MAX_BOOT_DEVS - 1] = { 0 };
     DeviceState *dev_st = get_boot_device(0);
     Object *machine = qdev_get_machine();
 
@@ -638,12 +637,22 @@ static bool s390_init_all_iplbs(S390IPLState *ipl)
             dev_st = get_boot_device(i);
             s390_build_iplb(dev_st, &iplb_chain[i - 1]);
         }
+    }
 
-        ipl->qipl.next_iplb = cpu_to_be64(s390_ipl_map_iplb_chain(iplb_chain));
+    /*
+     * Allocate maximum space for IPLB chain and/or certificate storage.
+     * Once a valid boot device is found, this space will be used to store
+     * certificates if secure boot is enabled.
+     */
+    if (iplb_num > 1 || s390_has_certificate()) {
+        ipl->qipl.ipl_data = cpu_to_be64(s390_ipl_map_iplb_chain(iplb_chain,
+                                                                 MAX_BOOT_DEVS - 1));
     }
 
     return iplb_num;
 }
+QEMU_BUILD_BUG_MSG(sizeof(IplParameterBlock) * (MAX_BOOT_DEVS - 1) != CERT_BUF_SIZE,
+                   "certificate buffer size is wrong");
 
 static void update_machine_ipl_properties(IplParameterBlock *iplb)
 {
diff --git a/include/hw/s390x/ipl/qipl.h b/include/hw/s390x/ipl/qipl.h
index a2180719b1..58329fb5bc 100644
--- a/include/hw/s390x/ipl/qipl.h
+++ b/include/hw/s390x/ipl/qipl.h
@@ -42,6 +42,7 @@ typedef enum S390IplType S390IplType;
 #define S390_IPLB_MAX_LEN 4096
 
 #define MAX_CERTIFICATES  64
+#define CERT_BUF_SIZE     (7 * 4096)
 /* largest supported block size - same as VIRTIO_DASD_DEFAULT_BLOCK_SIZE */
 #define VIRTIO_MAX_BLOCK_SIZE   4096
 #define MAX_COMP_ENTRIES        ((VIRTIO_MAX_BLOCK_SIZE - 32) / 32)
@@ -61,7 +62,7 @@ struct QemuIplParameters {
     uint32_t boot_menu_timeout;
     uint8_t  reserved3[2];
     uint16_t chain_len;
-    uint64_t next_iplb;
+    uint64_t ipl_data;
 } QEMU_PACKED;
 typedef struct QemuIplParameters QemuIplParameters;
 
diff --git a/pc-bios/s390-ccw/iplb.h b/pc-bios/s390-ccw/iplb.h
index c92a3d0f0c..c807e7f49b 100644
--- a/pc-bios/s390-ccw/iplb.h
+++ b/pc-bios/s390-ccw/iplb.h
@@ -61,11 +61,11 @@ static inline bool load_next_iplb(void)
     }
 
     qipl.index++;
-    next_iplb = (IplParameterBlock *) qipl.next_iplb;
+    next_iplb = (IplParameterBlock *) qipl.ipl_data;
     memcpy(iplb, next_iplb, sizeof(IplParameterBlock));
 
     qipl.chain_len--;
-    qipl.next_iplb = qipl.next_iplb + sizeof(IplParameterBlock);
+    qipl.ipl_data = qipl.ipl_data + sizeof(IplParameterBlock);
 
     return true;
 }
-- 
2.54.0